Black line photographic sensitized paper and process of making the same



l 9 i 7 May 19, 1901. OMOTO 1,805,592

BLACK LINE PHOTOGRAPHIG SENSITIZED PAPER AND PROCESS OF MAKING THE SAMEOriginal Filed Jan. 25, 1928 Thin layer of tannic ac id or similarsubstances produced from the second coating of volatile liquid in whichthe aboveare dissolve.

Thin g elatine filmmade of the first coating of ferric Paper wel l sizedwith salts, am-nonlum sulpho-cyanicl, alum-gelatine water etc. ingelatine solution INVENTOR. R. Omozfo A TTORNEYQ.

Patented May 1 9, 1931 UNITED, STATES PATENT OFFICE RYO onoro, orrenown, arm, nssrenon or one-mm 'ro mnnnu mm, or mono, rerun BLACK LINEPHOTUGRAPHIG SENSITIZED PAPER, Alll'D PROCESS OF MAKING- THE SAMEApplication filed January 25, 1928, Serial No. 249,504, and in JapanFebruary 9,1927. Renewed March 27, 1931.

ter in much the same manner as ordinarily blue-print papers aremanipulated. In my invention, I furthermore provide 'means whereby theoperator can easily tell when-exposure of the paper is completed.

In the process of making my paper, I first coat paper with a solutioncontaining a plurality of ferric salts, a. sulpho-cyanide and tartaricacid.

In manufacturing the paper, the liquid for the first coating is appliedto a thin tenacious ,sheet such as the Japan Simili parchment aper, andthe so treated paper is then dried. e constituents of the liquid andtheir relative quantities are not to be arbitrarily determined, but maybe suited to various requirements. An example of the mixture is asfollows Grams Ferric sulphate 2 Ferric chloride 3 Tartaric acid 2Gelatine. 2 Ammonium sulpho-cyanide 1 Distilled water 30 Then a solutionof tannic acid or similar substances in. a volatile solvent is appliedto the paper coated. with the ferric salt solution.

The components of this solution and their corresponding percentage arenot fixed, but

meet the requisites on the occasion. An example is as follows:

Ether 80, c. c. Alcohol- 20 c. c.

Tannic Acid.. 15 gms.

The essentials of this invention, as already stated above, reside inmixing a sulphocyanide salt with the ferric salt .solution and in usingvolatile liquids in which the tannic acid 'or similar matters aredissolved.

The reason ,why the two ferric salts are mixed together may easily beexplained by the fact'that the resulting black coloration of lines aredistinctive, while the sole application of each single ferric saltproduces only light black color; The tartaric acid sensitizes theferric-salts, which change to ferrous salts, when they are exposed tosunshine or intense electric light. These ferrous salts are notinfluenced by the tannic acid. The gelatine serves as an adhesive tobind the paper and the mixture, while it prevents the liquid frompermeating the sheet of paper. The sulphocyanide salt alters the naturallemon-yellow color of the fluid to 'a deep scarlet, which becomescolorless, when the paper is exposed to light, and thus serves to enablethe operator to determine when the printing is finished.

In the second coating, ether or other volatile liquids serve, on the onehand, to make the tannic acid or similar substances assume the form ofpaste, in which condition the coating operation is greatly facilitated,and

. adhesion after drying is perfected, while they inhibit, on the otherhand, the chemical combination of the tannic acid with the ferric salts,thusv preventing the production of blacln'sh substances.

In the accompanying drawing the thin layer, 1, of tannic acid or similarsubstances is placed on the thin gelatine film, 2, made of the firstcoating of ferric salts, ammonium sulpho-cyanid, etc., in gelatinesolution which is applied on a tenacious thin paper sheet, 3, well sizedwith alum-gelatine water.

Now-in the actual practice, after the exposure to light the ferric saltslying under the black lines of the original transparent drawing fromwhich the print is made will combine with the thin layer of the tannicacid when the paper is soaked in water, and in such a way black lineduplicates are secured.

In the exposed surface, the ferric salts are converted to ferrous-saltswhich produce no colored material in the presence of the tannic acid.

Ferric salt papers, hitherto prepared are of aninconspicuouslemon-yellow color, the observation of which, in measuringthe degree of whitening when exposed to light, is a matter of greatdiificulty, while with my paper, it being colored a deep scarlet, theoperator can easily determine the degree of exposure by the whitening.Some papers on the market use a special developing liquid after exposureto light to develop the black lines.

This process, however, is somewhat complicated in operation, and theblack lines printed are not satisfactory in color intensity and thefinishing of the blank surface of the paper is not clear unless theprinted paper is subjected to some bleaching chemicals which weaken theprinted black lines. Others are made by pressing and rubbing the surfaceof the ferric salt coating with powder of the gallic acid. In thismethod the operation of pressing and rubbing the slippery surface of thepaper as well as the degree of adhesion of the powder to the firstcoating may not be expected to be satisfactory as a matter of fact.Consequently, the black lines secured are not satisfactory and lackuniformity. In this process the sensitized paper can only be kept in itsoriginal condition for a short time after manufacturing, as the acidicand alkaline chemicals will gradually spoil the cellulose of the papersheet, .which loses its tenacity and becomes too frail to endurewashing. Gelatine, that has the merit of absorbing chemicals to guardthe cellulose of paper against spoiling, can not be used in thisprocess. For, in case gelatine be a component of the coating, the gallicacid powder is not fixed on the gelatinous slippery surface.

In m process, the volatile pasty solution is applied on the gelatinouscoating. Therefore, the operation is simple, easy, complete and evenover the whole surface. And as the thin layer of the second coatingadheres tightly to the first, the black lines thus revealed are clearlyprinted and retain intensity of color.

The manipulation of my paper is practically the same as when usingordinary blueprinting photo paper. The new paper is placed under theoriginal transparent drawing in a frame and exposed to sunshine or anelectric arc-light, and when those portions of the paper, over whichblack lines or spots of the original transparent drawing do not exist,have lost their original scarlet color and turn white, the exposed paperis taken off the frame and soaked in water.

well sprinkled with water, the

.the scope of the invention as claimed, and,

accordingly, therefore do not wish to be limited to the detailsdescribed herein.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. A sensitized photographic paper comprising paper having a coating offerric salts and a superposed coating of tannic acid.

2. A sensitized photographic paper comprising paper-having a coating offerric salts and a soluble sulphocyanide, and a superposed coating oftannic acid.

3. A sensitized photographic paper comprisin paper having a coating offerric salts, a solu le sulphocyanide, tartaric acid and gelgtine, and asuperposed coating of tannic aci 4. The process of making a sensitizedphotographic paper which comprises coating a paper with asolution offerric salts containing a soluble sulphocyanide, drying the coated paperand then applying a solution of tannic acid in a volatile solventthereto.

In testimony whereof I hereby afiix my signature this 28th day ofDecember, 1927.

RYO OMOTO.

